Green High School Graduation Caps. The Gradshop mortarboard graduation caps are of superior quality and ideal for all high school graduation ceremonies. The green grad cap is made of the same shiny green tricot fabric as the Gradshop graduation gowns. The mortarboard measure 9.4"sq and the headband has elastic at the headband for additional grip and comfort as well as 'one size fits all'. You can also order your choice of tassel from a selection of colors when you shop online at great low prices.